Walking beam furnaces

ABSTRACT

An arrangement in walking beam furnaces of the type having at least one walking beam which extends substantially in the feed direction of the furnace, and stationary supporting beams arranged adjacent to each walking beam, on both sides thereof, wherein the long sides of each walking beam in at least certain portions of the furnace form an angle with the feed direction of the walking beam.

United States Patent Inventor John Erland Erixson [50] Field of Search 263/6, 6 A;

Vasteras, Sweden i98/219 Appl. No. 846,870 Filed Aug. 1, 1969 [56] References Cited Patented Julie 1971 UNITED STATES PATENTS Assign 5mm mmllmkens Aktielmlag 3,398,939 8/1968 Morton 263/6 A Vasteras, Sweden I priority Aug 2, 1963 Primary Examiner-Charles Myhre Sweden Att0rneyStevens, Davis, Miller & Mosher ABSTRACT: An arrangement in walking beam furnaces of the t e havin at least one walkin beam which extends sub- WAL,KING M FURNACES stanti slly in th e feed direction of tie furnace, and stationary 2 Chums 5 Drawing Figs supporting beams arranged adjacent to each walking beam, on US. Cl 263/6A both sides thereof, wherein the long sides of each walking Int. Cl ..B65g 25/04, beam in at least certain portions of the furnace form an angle F27b 9/14 with the feed direction of the walking beam.

3O 29 l K\ 2\ \XA PATENTED JUN29 IQYI SHEET 1 [IF 2 PATENTEU JUN29 I97! SHEET 2 BF 2 WALKING BEAM FURNACES The present invention relates to an arrangement in walking beam furnaces, including at least one movable walking beam which extends substantially in the feed direction of the furnace, and stationary supporting beams arranged adjacent to each walking beam, on both sides thereof.

When heating goods in walking beam furnaces or subjecting goods to heat treatment therein, the portions of the goods under treatment located above the gaps between the stationary and moving beams are heated to a lesser extent than the remaining portions of the goods. In many cases the lower temperature of these portions is of small or no importance, but when greater demands are placed on quality and tolerances such temperature differentials cause disadvantages.

The main reason for uneven heating of the goods is seemingly due to the heat lost by radiation and convection taking place at the gaps between the stationary and movable beams. One way of reducing these heat losses is to make the gaps as small as possible. Heat is lost, however, even in the case of very small gaps, the loss affecting the goods material at the same position during the entire heating operation.

For the purpose of eliminating the harmful effect of heat losses on the goods being heated or subjected to heat treatment ant to provide for more uniform heating of the material in the furnace, it is suggested in accordance with the invention that in furnaces of exposed type aforedescribed the walking beam be tapered along at least a part of its length. Thus, in this way the same portion of the goods being treated is not always exposed to the areas of lower heat which exist at the gaps between the stationary and movable beams during the passage of said goods through the furnace, so that the temperature differences in the material of the goods are kept relatively low.

The invention will how be described in more detail with reference to a number of embodiments illustrated in the accompanying drawings, further characteristic features of the invention being disclosed in conjunctions therewith. Like elements in the drawings are designated with like numerals.

' In the drawing FIG. 1 shows diagrammatically a longitudinal-sectional view in vertical projection of a walking beam furnace,

FIG. 2 is a fragmentary cross-sectional view of the furnace illustrated in FIG. 1,

FIG. 3 is a view of the furnace illustrated in FIGS. 1 and 2, in horizontal section, showing an embodiment of the beam arrangement according to the invention, and

FIG. 4 is a view similar to the view of FIG. 3, and illustrates an additional embodiment of the beam arrangement according to the invention.

In the exemplary embodiment of FIGS. 1-3, the hearth of a walking beam furnace, selected purely by way of example, comprises two movable walking beams and stationary supporting beams 11, which extend adjacent the walking beams, on both sides thereof. The illustrated furnace has only one heating zone, 12, which is heated by means of appropriate burners 13 arranged in the end wall of the furnace at the discharge end thereof. Obviously this arrangement is not restrictive of the invention, and more zones may be provided and different burner arrangements may be employed. The waste gases are passed from the furnace through an exhaust outlet 14 located at the infeed end of the furnace.

The walking beams 10 rest on support wheels 15 journaled in angle arms 16, which in turn are journaled in bearing blocks 17 attached to stands 18. Connected to the arms 16 via a pull rod 20 is a hydraulic lifting cylinder 19, by means of which the movable beams can be raised and lowered in a known manner.

ble beams can be raised and lowered and moved horizontally back and forth are suitably capable of being adjusted, to enablc these limits to be adapted in the most convenient manner to the goods, the dimensions for which the furnace has been constructed. The time interval between two succeeding beam cycles, comprising moving the beam rearward, raising the beam, moving the beam forward and lowering the beam, is also preferably capable of being varied. In FIG. 2 the walking beams 10 are shown with full lines in a lowered position and with chain lines in a raised position.

Provided beneath the gap around each beam is a liquid trap 24, adapted to seal the furnace space from the beam machinery room 22 beneath the hearth and to collect scale and/or slag dropping from the goods 23. The chutes of the liquid trap 24 are constructed so that they can be cleaned of scale and other impurities falling therein through the aforementioned gaps. The goods 23 are fed to the furnace through a charging hatch 25 by means of a ram device 26, and are advanced intermittently through the furnace, to be finally pushed onto an outfeed chute 27 and leave the furnace through an exit hatch 28.

In order to prevent the same portions of goods 23 from being positioned over the gaps 29 between beams 10, 11 during the total stay time in the furnace, in accordance with the invention, the direction in which the long sides of each walking beam extend forms an angle in at least certain portions of the furnace with the feed direction of the walking beam. In the embodiment of FIG. 3 this is realized by the special construction of the walking beams 10, which taper along the whole of their length towards the discharge end of the furnace. The feed direction of the walking beams is shown by arrows 30.

FIG. 4 illustrates another embodiment of the beam arrangement of the invention. In this embodiment, the walking beams 31 only taper at those portions thereof situated nearest the discharge end of the furnace, while the long sides of said beams 31 and the adjacent long sides of the supporting beams 32 nearest the infeed end of the furnace extend in a known manner, parallel with the feed direction 30 of the walking beams.

When using the tapering walking beams of the embodiments shown in FIGS. 3 and 4, the walking beams 10 or 31 are suitably held advanced in rest position between the walking cycle, to such an extent that the gaps 29 between the supporting beams and the walking beams 10 and the tapering portions of beams 31 respectively become small, or are essentially eliminated. The hearth of the furnace is thereby essentially sealed and the heat losses are small, so that the temperature differences in the material of the goods are further equalized when the walking beams are stationary.

The beam arrangement of the invention is not restricted to the shown and described embodiments, but can be varied within the scope of the following claims.

Iclaim:

1. In a walking beam furnace including at least one movable walking beam which extends substantially in the feed direction of the furnace, and stationary supporting beams arranged adjacent to each walking beam on both sides thereof, the improvement comprising the provision that the walking beam tapers along at least a portion of its length.

2. An arrangement according to claim 1, in which the beam tapers along the whole of its length. 

1. In a walking beam furnace including at least one movable walking beam which extends substantially in the feed direction of the furnace, and stationary supporting beams arranged adjacent to each walking beam on both sides thereof, the improvement comprising the provision that the Walking beam tapers along at least a portion of its length.
 2. An arrangement according to claim 1, in which the beam tapers along the whole of its length. 